Dishwasher with rotatable spray member speed control means



Dec. 10,1968 R. J. GILSON 3,415,258

DISHWASHER WITH ROTATABLE SPRAY MEMBER SPEED CONTROL MEANS Filed May 231966 1 2 Sheets-Sheet l 2%)); A 1/, Mg

Dec. 10, 1968 R. J. GILSON 3,415,258

DISHWASHER WITH ROTATABLE SPRAY MEMBER SPEED CONTROL MEANS United StatesPatent 3 415,258 DISHWASHER WITH RbTATABLE SPRAY MEMBER SPEED CONTROLMEANS Robert John Gilson, Naphill, England, assignor to Charles ColstonLimited, High Wycombe, England, a corporation of the United KingdomFiled May 23, 1966, Ser. No. 551,999 Claims priority, application GreatBritain, May 28, 1965, 22,746/65, and 22,747/65 7 Claims. (Cl. 134-112)ABSTRACT OF THE DISCLOSURE A dishwasher of the type including anelongated rotatable reaction jet operated spray member having jetreaction means spaced along its longitudinal axis about which it rotatesincluding braking means for restricting the speed of rotation of thespray member without reducing the rotation producing torque applied bythe reaction jet means. The speed of rotation is so restricted, as forexample, by viscous fluid braking means, that spray pulses are deliveredby the jet reaction means so timed as to allow spent surface waterresulting from one pulse to drain away from a soiled dish surface beforethe next pulse arrives, best results being obtained when the pulses aretimed to arrive at intervals of not less than about half a second.

This invention relates to dishwashers of the type in which the washingliquid is discharged from a spray member revolving about an axisextending through a clear path between the dishes, the spray memberactually being caused to rotate by jet reaction or by reaction with theincoming liquid. The rotary spray member may take the form of anapertured spray tube, or an equivalent elongated rotary member capableof discharging spray or jets all along and around its path of rotation.

It has hitherto been the practice to operate such a spray member at arotational speed of anything from 100 r.p.m. to 1,000 r.p.m. I have nowfound that a markedly improved washing action can be achieved if thespeed of rotation is much reduced, e.g. to below 120 r.p.m. andpreferably as low as, say, 10 or r.p.m.

With a spray member operating at the customary speed of rotation, thedishes are, for all practical purposes, immersed in a heavy continuousrain of spray drops, with the result that newly-arriving drops impingeon and are dissipated by spent surface water resulting from previousdrops which have not had time to drain off. In contrast to this, whenthe rotational speed is considerably reduced, the spray jets impinge onany one dish in a series of intermittent pulses timed sufiiciently farapart to allow the spent surface water resulting from one pulse to drainaway from the soiled surfaces before the next pulse arrives; thus thefull energy of each newly-arriving pulse is available to act on anyparticles of food adhering to the dishes at given points. I have foundthat the best results can be obtained when the spray pulses are timed toarrive at intervals of anything from about half a second to about fiveseconds.

An obvious way to reduce the speed of rotation of a spray member, drivenby reaction of or with the liquid, is to reduce the driving torque; forinstance, if the spray member is caused to rotate by jet reaction, areduction of speed can be obtained by directing some or all of the jetsin a more nearly radial direction, or by counteropposing some of thejets. I find, however, that if this simple method is adopted, thedriving torque becomes too low to provide reliable operation, inasmuchas there is insufiicient margin of torque to overcome the retardingeffect that can be caused occasionally by small food par- P CC ticleslodging in the gap between the spray member and the associatedliquid-supply fitting, or in the bearing surface clearances. What isneeded is a means of reducing the speed without reducing the drivingtorque, and preferably, of course, without having to resort to any formof geared drive or other mechanical elaboration.

According to the invention a method of operating a dishwasher comprisessupplying liquid under pressure to a spray system including an elongatedrotary spray member revolving about an axis extending through a clearpath between dishes to be washed, applying a rotational torque to therotary spray member by reaction of the liquid supplied thereto onreaction surfaces or jet orifices comprised by the spray member, andapplying speed responsive braking to said spray member to restrict andcontrol the speed of rotation of the latter without reducing the torqueapplied thereto. Since the degree of braking will be related to thespeed of rotation of the spray member, a governor action will beobtained which will control the speed of rotation of the spray memberwithin reasonably close limits, without any reduction in the torqueapplied to the spray member, this torque being fully available toovercome any tendency to jamming by food particles or the like.

In practice, it is preferred to obtain the braking effect by introducingviscous drag between the revolving member and the fixed axle or supporton which it is mounted to rotate. I find that in this way it is readilypossible to reduce the speed to only a small fraction (e.g. 5%) of whatit would be without the braking effect, whilst retaining the maximumpossible driving torque to guard against the above mentioned possibilityof occasional jamming by food particles or debris.

According to the invention also a dishwasher comprises a spray systemincluding an elongated rotary spray member, revolving about an axisextending through a clear path between dishes to be washed and providedwith jet orifices or reaction surfaces designed on discharge of jets ofliquid therefrom to impart by reaction a substantial rotational torqueto the spray member, and speed responsive braking means to restrict andcontrol the speed of rotation of said member without reducing the torqueapplied thereto.

A further object of the invention is to provide an improved constructionof spray member which will be less liable to clogging than conventionalspray tubes and will provide an improved washing action by improving theefliciency with which the energy of the pressurized fluid supplied tothe spray member is converted into the kinetic energy of the spray.

When a spray tube is used, the holes in the tube are necessarily of sucha size that they can occasionally become clogged by debris such as eggshell or fruit pips. Furthermore, the jets from the holes in a spraytube lack solidity since the holes are little more than apertures in athin wall, and for the same reason the change in direction andconditions of flow adjacent the holes is fairly drastic, leading toenergy losses due to turbulence. Also, in a spray tube, any leakage ofliquid other than through the holes leads to loss of efficiency.

According therefore to a further feature of the ir1- vention, a spraysystem for a dishwasher comprises the combination of a fixed nozzlemember, arranged to direct a jet or jets along a path between articlesto be washed, and a spray member comprising a columnar deflector member,rotatably mounted on a fixed axle extending in the direction of the jetor jets and substantially central thereto, the deflector member beingprovided with one or more series of jet deflector channels, successivechannels in the or each series being spaced circumferentially of andalong the length of the axis of rotation, so as successively tointercept the jet or jets and redirect it or them onto the articles,when positioned in the washing chamber, the said channels beingnon-radially disposed so that the reaction of the deflected jet or jetsexerts a torque causing rotation of the deflector member.

In a preferred embodiment of this latter feature, the columnar deflectormember is made up of a number of stepped elements, mounted on a commonsleeve rotatable on the axle and so arranged that successive elementsoverlap and are thus staggered circumferentially and in the axialdirection to form channels, which cut across and intercept the jetsduring rotation resulting in the discharge of radiating jets over thelength of the deflector member. Each element may consist of a hub orcollar, having a radially extending portion, which portion, when viewedaxially, is curved so that the direction of jet discharge is non-radial,thus providing a driving torque which causes the stack of elements torotate on the axle.

The main advantages of this construction over the widely-used aperturedspray tube are:

(1) The danger of clogging by food particles or debris is greatlylessened. The apertures in a spray tube are necessarily of such sizethat they can occasionally become clogged by debris such as egg-shell,fruit pips, etc., whereas the channels in the deflector column of thepresent invention are open-sided and also are tapered in width so as towiden out in the direction of flow. Not only are they therefore muchless prone to clogging, but, in the unlikely event of a piece of debrisbecoming wedged in, it is readily seen and removed, without anydismanfling. The nozzle apertures in the fixed nozzle member being muchlarger than the apertures in a spray tube, are not prone to clogging.

(2) Possibility of decreased washing action due to leakage of liquidentering the spray tube is eliminated as also is jamming or reduction inspeed due to small food particles lodging in the gap between the spraytube and its associated liquid supply fitting.

(3) The jets from the apertures in a spray tube lack solidity, since theapertures are little more than holes in a thin wall. In contrast, thenozzle oulets in the fixed nozzle member used in the system of thisinvention can have the correct form and adequate length to provide fullcontrol of jet formation, and can thus provide really solidhigh-velocity jets with a minimum of turbulence or other losses. Alsothe local deflector channels can provide a smooth shock-free change ofdirection with the minimum of energy losses; in contrast the change indirection and conditions of flow at the apertures in a spray tube is farmore drastic. The net result is that the jets impingng on the dishes,are markedly stronger and more effective in the case of the presentsystem than can be obtained from the customary spray tube arrangements.

(4) The deflector channels can be so shaped as to deflect the primaryjets through an angle greater than 90 so as to point backwardsrelatively to the primary jets. This can be very advantageous insecuring good washing action on closely stacked plates and on deeplydished items such as soup plates or cereal bowls.

(5) The combination of the high-efficiency jets given by the deflectorchannels with the very slow rotational speed of the spray memberprovides a marked improvement in washing efliciency. Whereas it has beencustomary to use a rotational speed of anything from several 100 rpm. upto several 1,000 rpm. where a rotary spray tube is used, I have foundthat improved washing action can be obtained if the speed is kept below100 rpm. and preferably as low as say or rpm.

A preferred embodiment of the invention is described with reference tothe accompanying drawings, in which:

FIG. 1 is a section through the axis of the outer end of a spray member,

FIG. 2 is a similar section through the inner end of a spray member andadjacent parts,

FIG. 3 is an elevation of the inner end of the spray 4 member of FIG. 2,with the shroud described below omitted for clarity,

FIG. 4 is an end elevation of the spray member, as viewed from the leftof FIG. 3, additionally showing the shroud,

FIG. 5 is a part plan view of the inner end of the spray member.

Referring first to FIG. 1, a fixed axle 2 carries a spray member 4,journalled on the outer end of the axle by an end plate 6. Although itis preferred that the spray member is of the construction describedbelow, it should be understood that any reaction driven rotary spraymember having an axis extending through a clear path between the dishesto be washed may be substituted and that the performance of such a spraymember will benefit from use of the arrangement shown in FIG. 1.

To the end of the axle 2, a disc 8 is made fast by means of a screw 10engaging a threaded bore 12 in the axle. The disc is housed in aconfined chamber 14 formed between the end plate 6 and a housing 16. Thehousing 16 is closed by a screw plug 18 screwed into a threaded orificein the housing so as to take up play between itself and the head of thescrew 10, thus in combination with the end plate 6 and the disc 8retaining the spray member 4 on the axle.

The chamber 14 is filled through a screw plug 20 with a high viscositydampening fluid, which may for example be a silicone dampening fluidhaving a viscosity in the region of 10,000 to 100,000 centistokes. Sucha fluid has the advantage of showing a relatively small change inviscosity over the working temperature range. It will be clear that thedesired speed of rotation may be obtained by suitable selection of thethickness of the film between the disc 8 and the inner surface of thechamber 14, as well as of the viscosity of the fluid. It is mostimportant that the liquid in the chamber 14 be isolated from the washingliquid, as the ingress of even very small quantities of the latter intothe chamber will greatly reduce the drag effect of the silicone fluid. Aseal 52 retained by a collar 54 is therefore provided to prevent ingressof washing liquid between plate 6 and axle 2.

Referring now to FIGURES 25, liquid from a circulatory pump (not shown)flows through a transfer duct 30 and emerges as jets 32 from a nozzle orcluster of nozzles 34 formed in a nozzle member 36 attached to one ofthe walls 38 of the washing chamber. The fixed axle 2 projects from thenozzle member in the same direction as the jets, and a series of steppedelements having radially and axially extending portions 42 are mountedby means of root portions 43 on a tubular sleeve 44 journalled to rotateon the axle 2; the elements are shaped at their ends nearest the nozzlesto form channels 46 which cut across and intercept the jets 32 duringrotation, resulting in the discharge of radiating jets 48, spaced overthe whole length of the spray member so as to spray the dishes which canbe supported in suitable racks arranged within the washing chamber tosurround the spray member.

A shroud 50 encloses the space around the sleeve 44 swept by the jets 32except in the immediate vicinity of the channels 46. This prevents unduespread of the primary jets 32 and thus helps maintain satisfactory sprayformation. The channels 46 widen out and are smoothly and continuouslycurved in the direction of liquid flow to obtain a smooth change ofdirection in the liquid intercepted thereby, whilst the portions 42 andhence the channels present a curved cross section in a plane at rightangles to their rotational axis so that the secondary jets 48 aredischarged non-radially, their reaction providing the driving torque forthe spray member.

It should be understood that the embodiment illustrated, i.e. acomposite column built up by stacking overlapping individual elements ona common sleeve, is only one of many possible methods of fabrication.The principle involved, is the use of a columnar group of jet-deflectorchannels spaced over the effective length of spray discharge in the formof a staggered row or rows, covering substantially 360 in end view, andmounted for rotation about an axis located at the centre of the clusterof fixed jet-nozzles so that during rotation, each said channel cutsacross each said jet and in so doing, re-directs or deflects the jetthrough approximately 90 so as to cause it to impinge on the surroundingdishes. Each primary jet will therefore give rise to as many secondary,dish impinging, jets as there are channels, each secondary jet geingdirected to a separate zone of the washing cham- The use of staggeredrows of channels subtending approximately 360 in end view is desirable,since if less than 360 in end view is covered, then some of the jets 48will pass straight through the cluster of channels and be wasted, whilstconversely, if more than 360 is covered then the individual channelsmost remote from the nozzle end will be starved of liquid. In thearrangement of FIG- URE 4, there are three rows of channels 46, eachspread over approximately 120 of arc in end view. Alternativeconstruction comprises two rows each of 180, four rows each of 90, orone row of 360.

The channels are shaped to deflect the jets 48 through rather more than90 in side elevation, as shown by the jet 48 directional arrows, but itwill be understood that the precise angle of deflection can be eithermore or less than 90, depending on the precise position in which theplates and dishes are located.

When the spray device is mounted horizontally within the washingchamber, the nozzles 34 formed in the fixed nozzle member 36, may bedirected slightly upwards, i.e. at an angle of say one or two degrees tothe axis of the fixed axle, in order to compensate for the slight fallin the trajectory of the jets over the length of the column of elements.

It is found that the slow speed of rotation (preferably 5-50 r.p.m.) ofthe deflector column due to the arrangement of FIGURE 1 results inmarkedly superior washing action, and also it eliminates problems ofvibration due to out-of-balance of the rotating column.

What I claim is:

1. A dishwasher comprising a spray system including an elongated spraymember having spray jet reaction means spaced axially along itslongitudinal extent; means mounting said member to extend through aclear path between positions of dishes to be Washed and for rotationabout its own longitudinal axis; means for delivering liquid to saidmember for discharge from said spray jet reaction means thereby toimpart a torque to said spray member for rotating the latter; and speedresponsive braking means for restricting the speed of rotation of saidmember without reducing said torque, said braking means so restrictingsaid speed of rotation of said member that spray pulses delivered bysaid jet reaction means are timed to arrive at given points on dishesbeing washed at intervals of not less than about half a second.

2. A dishwasher according to claim 1, in which the speed responsivebraking means comprises a film of viscous liquid, isolated from thewashing liquid between a surface associated with the spray member and asurface associated with a part on which the spray member is journalled.

3. A dishwasher according to claim 2, in which the surface associatedwith the part on which the spray membet is journalled is the surface ofa disc fast to said part, and the surface associated with the spraymember is the inner surface of a confined chamber enclosing the disc andfast to the spray member said chamber being completely closed againstingress of washing liquid by means including a seal between said spraymember and said means mounting said spray members.

4. A dishwasher according to claim 2, in which the spray systemcomprises a fixed nozzle member positioned to direct, on the supply ofliquid under pressure thereto, fluid along a path between articles whenpositioned in a washing chamber, the spray member comprising a columnardeflector member, rotatably journalled on a fixed axle extending in thedirection of the jet fluid and substantially central thereto, thedeflector member being provided with serial outwardly extendingdeflector channels, serially successive channels being spacedcircumferentially of and along the length of the axis of rotation,whereby successively to intercept the jet fluid on rotation of themember and re-direct it onto the articles, the outer ends of thechannels being non-radially disposed whereby the reaction of thedeflected jet fluid exerts a torque causing rotation of the deflectormember.

5. A dishwasher according to claim 1, in which the spray systemcomprises a fixed nozzle member positioned to direct, on the supply ofliquid under pressure thereto, jet fluid along a path between articleswhen positioned in a washing chamber, the spray member comprising acolumnar deflector member, rotatably journalled on a fixed axleextending in the direction of the jet fluid and substantially centralthereto, the deflector member being provided with serial outwardlyextending deflector channels, serially successive channels being spacedcircumferentially of and along the length of the axis of rotation,whereby successively to intercept the jet fluid on rotation of themember and re-direct it onto the articles, the outer ends of thechannels being non-radially disposed whereby the reaction of thedeflected jet fluid exerts a torque causing rotation of the deflectormember.

6. A dishwasher according to claim 5, in which the channels widen outand are smoothly and continuously curved in the direction of flow.

7. A dishwasher according to claim 6, in which the path swept by thejets before deflection is enclosed by a shroud except in the immediatevicinity of the channels.

References Cited UNITED STATES PATENTS 1,386,734 8/1921 Rosenbaum 1341791,435,140 11/ 1922 Rolland 239-252 1,637,376 8/1927 Gibney 134-562,980,120 4/1961 Jacobs 134-183 XR 3,029,028 4/ 1962 Skerritt 2392S23,107,859 10/1963 Gilson 134174 XR 3,176,697 4/1965 Gibson 134-183ROBERT L. BLEUTGE, Primary Examiner.

US. Cl. X.R.

